Pyrolysis boiler and pyrolysis afterburning of fuel pellet burners

For each type of boiler, one characteristic that determines the efficiency is important. It consists in the maximum extraction of thermal energy from the burning fuel. This is the characteristic that a pyrolysis boiler is distinguished by. They are recommended for use with fuels with high volatiles yields. This applies to firewood, wood waste, fuel briquettes, agro and wood pellets. Some modern pyrolysis boilers can be fired with nut coal or even coke.

Principle of operation pyrolysis boiler

To maintain a normal pyrolysis reaction, compliance with fuel moisture requirements is required. It should not exceed 35%. Moreover, the less the better. This is due to the fact that pyrolysis gases are released and mixed with water vapor, which interferes with the gas generating reaction. With a very wet fuel, a pyrolysis boiler, unlike a solid fuel one, does not burn at all. So in the absence of dry fuel, you can generally be left without heating.

A pyrolysis boiler is a heating equipment that uses heat recovery. It consists in the afterburning of gases released during the combustion of fuel, mainly carbon monoxide, volatile hydrocarbons and nitrogen. Air is mixed with the gaseous combustion products, and they are burned out. Part of the heat energy is returned to the wood, which maintains a highly efficient combustion.

Design

The principle of operation involves a two-chamber design. The first chamber is gas generating, it is a conventional combustion chamber with fuel loading. When oxygen is limited, the fuel burns slowly, while releasing many volatile compounds. This effect is called fuel pyrolysis. The gases enter the second compartment, into which air is supplied, the so-called overhead blast. Combustion products burn together with air and generate heat.

Thus, a pyrolysis boiler is a long-burning boiler that runs on gas released during the combustion of the primary fuel. Accordingly, this type of heat source is distinguished by a two-chamber design and an overhead blowing, providing pyrolysis afterburning of gases.

This principle is implemented in modern pellet boilers. It is also provided by an automatic pellet burner FOCUS... Thus, efficiency is enhanced by a range of technologies.

It should be noted that pyrolysis boilers operate only on forced draft due to high aerodynamic pressure. It is realized as a smoke exhauster or fan for small boilers.

How additional heat is generated and the principle of long-term combustion of a pyrolysis boiler

Before starting the combustion cycle, fuel is loaded into the first combustion chamber. After firing up, the door closes tightly without air supply. The fuel smolders and charred with the release of gaseous compounds. This reaction is called pyrolysis. As a result of combustion, or rather smoke, hydrogen, carbon monoxide and volatile hydrocarbons are formed, as well as nitrogen from the supplied air.

At all stages of pyrolysis, heat is removed from the fuel and supplied to the heating system.

The pyrolysis afterburning of gases, provided by the design, makes the combustion intensity of the pellet burner more. For this reason pellet boiler efficiency turns out to be more, and fuel consumption is less.

Pyrolysis is one of the most important technical characteristics of pellet boilers.